At present, acid secretion inhibitors such as H.sub.2 -blocker and proton pump inhibitor, and mucosalprotective factor enhancers, have been mainly used for the treatment of peptic ulcers such as gastric ulcer and duodenal ulcer. While the use of H.sub.2 -blocker and proton pump inhibitor shortens treatment period, the problem of possible recurrence of the disease still remains to be solved.
Helicobacter pylori (H. pylori) is a Gram negative bacterium found in the mucous layer on the gastric epithelium of humans, and infection with H. pylori has been found to induce gastrointestinal diseases, such as chronic gastritis and peptic ulcer (e.g., gastric ulcer and duodenal ulcer). There are an increasing number of reports on the effectiveness of the eradication of H. pylori for treating intractable ulcers and prevention of ulcer recurrence. The drug having an antimicrobial action on H. pylori is useful for the treatment and/or prevention of gastritis and ulcer, and a new drug having such pharmacological action is desired.